Last year, my kid got off the bus at around 3:50pm. Dismissal was 3:30.
This year, dismissal at our ES will be at 3:50, and I'm guessing he'll get off the bus around 4:10 or 4:15 (like the PP said, I think there will be some extra traffic).
It probably depends on how far you are from the school, etc? Agree that you could ask around the neighborhood, but it'll be tough to predict this year since the times are different.